1. Field of the Invention
An improved universal flashing for roof top and vent pipe geometries characterized by differing pipe diameters and roof slope angles, which more effectively prevents water leakage, either past the seal between the flashing and the vent pipe, or between the roof and the base flange of the flashing.
2. Description of the Prior Art
Various prior flashings have been taught, wherein a flexible configuration is used to adapt to various vent pipe configurations, and varying roof pitch slope angles. The following patents are illustrative of the state of the prior art:
FIFE, U.S. Pat. No. 1,258,884 PA0 HOLLAENDER, U.S. Pat. No. 1,317,446 PA0 KIFER, U.S. Pat. No. 3,313,559 PA0 ELWART, U.S. Pat. No. 3,602,530 PA0 GUSTAFSON, U.S. Pat. No. 3,677,576 PA0 ELWART, U.S. Pat. No. 3,731,952 PA0 NAGLER ET AL., U.S. Pat. No. 3,945,163 PA0 LOGSDON, U.S. Pat. No. 4,010,578 PA0 NAGLER ET AL., U.S. Pat. No. 4,120,129
The present invention is distinguished over the collective teachings of the prior art in defining a flexible flashing peculiarly well adapted to seal against varying vent pipe diameters, while providing easy removal for sets of sealing projections from the sealing area, to accomodate installation upon a larger vent pipe diameter. While certain prior flashing teachings are analogous in that an elastomeric material is distended around a vent pipe for sealing thereof, the rooftop environment is quite hostile, and sealing difficulties often arise either from improper installation, or simple deterioration. The present invention allows differing vent pipe diameters (and varying roof pitch angles) to be sealed very firmly and effectively, since sets of frangible sealing projections successively are removed, for larger vent pipe diameter. The following brief discussion of prior art attempts at universal flashings, will illustrate the advantages of the present invention.
FIFE illustrates it long has been known to define a flashing to accomodate various pipe diameters and roof pitch angles. FIFE taught a frustoconical sheet metal base attached to a caulking sleeve of soft metal, such as lead. The lead is pounded into a tight contact with a pipe and is malleable enough to adjust to various pipe angles. A groove as a cutting guide is provided should a larger diameter pipe be fitted. Such soft metal flashings are still used today, but are prohibitively expensive and subject to improper fit, though they resist attack by high temperature roofing materials.
HOLLAENDER illustrates a pipe with lead flashing and corrugations to allow bending of the frustoconical member to fit various angles, with the pipe sealed by a ring clamp, to urge the pliable material around the vent diameter.
KIFER illustrates a dome-shaped sheet metal conduit with an elastomeric collar, wherein the collar has a slightly smaller diameter than the outer diameter of one pipe meant to pass therethrough, whereby the collar will distend and supply a tight seal. Flexibility of the collar is configured to allow the pipe roof angle to be slightly varied.
ELWART '530 illustrates one approach to an universal flashing, wherein cutting lines are defined at the bottom of a flexible, corrugations in an annular array, and further corrugations are provided in the frustoconical body of the flashing, to allow conforming to slightly different roof pitches.
GUSTAFSON illustrates an elastomeric collar wherein the wall contour and shape of the collar is configured so that a given pipe diameter will be engaged over a substantial distance, with different bell shaped wall structures required for 3" or 4" pipes, for example.
ELWART '952 is denominated an improvement over his earlier patent, wherein a rigid polyethelene, frustoconical member supports a separate neoprene O-ring seal, wherein further the rigid polyethelene member may be cut to expose another O-ring, for a larger pipe diameter.
NAGLER ET AL. '163 illustrates a moulded box type of roof flashing, wherein separate raised circular portions are provided to pass a pipe.
LOGSDON illustrates a two piece roof flashing structure wherein a separate resilient elastomeric sealing member is pivotable within a rigid retainer ring, so that a single pipe diameter can be oriented at various roof pitch angles.
NAGLER ET AL. '129 illustrates a seamless aluminum housing that supports a cap of elastomeric material, which must be selectively severed and a clamp then placed around the desired vent pipe diameter.
The present invention is distinguished from these prior art approaches by a dual-seal concept that is of simple construction, and whereby a different set of projections is available to accomodat each of up to four pipe diameters. The present invention also is distinguished from the prior art in a preferred embodiment by being entirely of a one-piece elastomeric material, such as flexible PVC, which enables not only various roof pitch angles easily to be accomodated, but also enables the flange surface effectively to seal against both a vent pipe diameter, and also a roof surface.